CEL on. 0171/0174. Easiest way to log fuel trims and clear DTCs?

[Jjmoberg]

Just put the tube section from the MACH1 back on the car and try it out. takes 5 minutes. The GT350 never had the carbon filter nonsense in it, and the sleeve is in place on the 22+ MAch1's to hold that carbon trap in place

Thats my plan. And maybe remove the driver side oil separator while i am at it. It had 0 drips of oil in it when i checked at my yearly oil change. The passenger side had an ounce or two maybe.

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[SheepDog]

Thats my plan. And maybe remove the driver side oil separator while i am at it. It had 0 drips of oil in it when i checked at my yearly oil change. The passenger side had an ounce or two maybe.

Replace/reinstall only a single item at a time, otherwise you will never know which part was the culprit

 

[Jjmoberg]

Replace/reinstall only a single item at a time, otherwise you will never know which part was the culprit

True that. I was just thinking of leaving the oil separator off either way

 

[engineermike]

Most likely culprit is an inaccurate maf transfer function.

 

[Jjmoberg]

Most likely culprit is an inaccurate maf transfer function.

I have thought of that, but dang that would be pretty far off for a tube that i think is the same diameter, and a ported throttle body. I was expecting to see 10%sh. Part of the issue is if i put the factory parts back on and the trims go to near 0, i wont necessarily know if that means i had a leak or if its just outflowing the MAF table. And i think if its truly just more air flow id rather the parts were on there and have it tuned for.

 

[engineermike]

What we know is you’re 4-5 weeks into this problem, the maf is not stock, the car was not tuned for the maf, maf not matching transfer function causes bad trims, and it takes just a few minutes to swap it out. Why haven’t you already done it?

 

[Jjmoberg]

What we know is you’re 4-5 weeks into this problem, the maf is not stock, the car was not tuned for the maf, maf not matching transfer function causes bad trims, and it takes just a few minutes to swap it out. Why haven’t you already done it?

The MAF is stock. Its sitting in a GT350 tube that is the same internal diameter as the M1 tube. The TB is a factory Soler ported unit.

 

[SheepDog]

The MAF is stock. Its sitting in a GT350 tube that is the same internal diameter as the M1 tube. The TB is a factory Soler ported unit.

What was the purpose of using the GT350 tube instead of the MACH1 tube?

I'd bet a dollar that the inner diameters are not the same. The GT350 never had the carbon trap in it, so it doesn't have the sleeve that holds it in place. The combination of the slight change in diameter, as well as putting Ethanol in the tank when it isn't tuned for it could easily give you a 25% discrepancy in fuel trims. I found this out the day I brought my MACH1 Home. Hastily went to remove the carbon trap, and didn't replace the sleeve. 20% fuel trims. Put the sleeve back in, trims normalized.

 

[Jjmoberg]

Got caught up in house projects today so i didn't have time to do anything other than drive it for 15 miles or so and just watch the trims after i reset adaptives last night. I am happy to out the stock parts back on tomorrow but i am confused about what i saw while driving.

I used the tuner for my truck and just watched LTFT bank 1, LTFT bank 2, STFT bank 1, and STFT bank 2.

It took LTFTs a few miles to start adjusting but they went to 1.26 bank 1 and 1.28 bank 2 and mostly stayed right about there. Meanwhile STFT was between .95 and 1.05 essentially the whole time. At idle, at low throttle acceleration, at half throttle acceleration, on cruise on the highway at 75mph, and a short WOT pull.

I thought LTs worked off of STs. Dont understand how stft can be so good and ltft so bad.

I cant imagine i have a vacuum leak with the STFTs so stable at every throttle and load position

 

[Jjmoberg]

I put the GT350 tube on there cause it looks better to me. CoastalMach had done it previously with no issues, though i dont know if he monitored trims. Its a nicer intake sound without the resonator box on the tube. Also i broke one of the tabs off of that inner sleeve on the M1 tube and it bugged me. It sits in there fine but it made me mad.

 

[mejohn50]

Got caught up in house projects today so i didn't have time to do anything other than drive it for 15 miles or so and just watch the trims after i reset adaptives last night. I am happy to out the stock parts back on tomorrow but i am confused about what i saw while driving.

I used the tuner for my truck and just watched LTFT bank 1, LTFT bank 2, STFT bank 1, and STFT bank 2.

It took LTFTs a few miles to start adjusting but they went to 1.26 bank 1 and 1.28 bank 2 and mostly stayed right about there. Meanwhile STFT was between .95 and 1.05 essentially the whole time. At idle, at low throttle acceleration, at half throttle acceleration, on cruise on the highway at 75mph, and a short WOT pull.

I thought LTs worked off of STs. Dont understand how stft can be so good and ltft so bad.

I cant imagine i have a vacuum leak with the STFTs so stable at every throttle and load position

Total fuel trims are LTFT+STFT. Small short term trims really only means long term trims are working.

 

[Dave2013M3]

I know i screwed up initially adding 2 gallons and not topping off. I just cant believe that hasnt trimmed out after 12 gallons and 100-125 miles of driving. So that makes me wonder if i have a leak or my set up is sitting at positive ltfts all the time and the E just pushes it over the edge. I need to be able to see the trims. And hopefully clear KAMs when needed.

Anyone have thoughts on Forscan lite?

I didn't read the whole thread, but topping off with 2 gallons of E shouldn't cause this.

 

[Jjmoberg]

I didn't read the whole thread, but topping off with 2 gallons of E shouldn't cause this.

My current guess is the intake tube + no carbon filter + the ported TB has my trims at 26%. The E put it over 30% and kicked the SES light.

 

[engineermike]

Ported tb will not affect fuel trims.

 

[ice445]

The gt350 tube doesn't have the helmholtz resonator like the Mach 1 tube, and the maf is located in a different place as well. I'd agree with Mike that the transfer function is off. It's probably been slowly raising the trims since you put it on, and then the e85 demand put it over the edge and got you to investigate it after codes popped.

Just put it back to stock.

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